Metformin and atorvastatin reduce adhesion formation in a rat uterine horn model

Effect of Metformin on HIF-1α Signaling and Postoperative Adhesion Formation

BACKGROUND

Peritoneal adhesion formation is common after abdominal surgery and results in severe complications. Tissue hypoxia is one of the main drivers of peritoneal adhesions. Thus, we determined the clinical role of hypoxia-inducible factor (HIF)-1 signaling in peritoneal adhesions and investigated whether the biguanide antidiabetic drug metformin shows HIF-inhibitory effects and could be repurposed to prevent adhesion formation.

STUDY DESIGN

As part of the ReLap study (DRKS00013001), adhesive tissue from patients undergoing relaparotomy was harvested and graded using the adhesion grade score. HIF-1 signaling activity within tissue biopsies was determined and correlated with adhesion severity. The effect of metformin on HIF-1 activity was analyzed by quantification of HIF target gene expression and HIF-1 protein stabilization in human mesothelial cells and murine fibroblast under normoxia and hypoxia. Mice were treated with vehicle or metformin 3 days before and until 7 days after induction of peritoneal adhesions; alternatively, metformin treatment was discontinued 48 hours before induction of peritoneal adhesions.

RESULTS

HIF-1 signaling activity correlated with adhesion severity in patient biopsies. Metformin significantly mitigated HIF-1 activity in vitro and in vivo. Oral treatment with metformin markedly prevented adhesion formation in mice even when the treatment was discontinued 48 hours before surgery. Although metformin treatment did not alter macrophage polarization, metformin reduced proinflammatory leucocyte infiltration and attenuated hypoxia-induced profibrogenic expression patterns and myofibroblast activation.

CONCLUSIONS

Metformin mitigates adhesion formation by inhibiting HIF-1-dependent (myo)fibroblast activation, conferring an antiadhesive microenvironment after abdominal surgery. Repurposing the clinically approved drug metformin might be useful to prevent or treat postoperative adhesions.

Metformin reduces ovarian ischemia reperfusion injury in rats by improving oxidative/nitrosative stress

OBJECTIVE

To assess the preventive role of metformin on rat ovarian ischemia reperfusion injury.

MATERIALS AND METHODS

Forty rats were divided equally into five groups; Group 1: sham, Group 2: surgical control with 3-hr torsion and detorsion, Group 3: 50 mg/kg p.o. metformin 30 min before 3-hr torsion, Group 4; metformin just after detorsion, Group 5; metformin 30 min before torsion and just after detorsion. Bilateral ovaries and blood sample were obtained seven days after detorsion for biochemical and histopathological evaluation.

RESULTS

Ovarian tissue total anti-oxidant status (TAS) levels were significantly increased in group 4 when compared to group 1, 2 and 3 (all p < 0.01). In addition, there was a significant decrease in tissue oxidative stress index (OSI) level in group 4 with respect to group 2 (p < 0.01). Moreover, serum levels of OSI were significantly higher in group 2 with respect to group 1 and 5 (both p < 0.05). Similarly, there was significant increase in serum levels of peroxynitrite in group 2 as compared to serum levels in group 3 and 5 (p < 0.01 and 0.05, respectively). Furthermore, there were significant decrease in histopathological scores metformin and sham groups when compared to rats in the control group (Group 2).

CONCLUSION

Metformin reduces ischemia reperfusion injury in rat torsion detorsion model by improving histopathological and biochemical findings including TAS, OSI and peroxynitrite.

Association Between Statin Use at the Time of Intra-abdominal Surgery and Postoperative Adhesion-Related Complications and Small-Bowel Obstruction

IMPORTANCE

Adhesion-related complications (ARCs), including small-bowel obstruction, are common complications of intra-abdominal surgery. Statins, which have antifibrotic pleiotropic effects, inhibit adhesion formation in murine models but have not been assessed in humans.

OBJECTIVE

To assess whether statin use at the time of intra-abdominal surgery is associated with a reduction in ARCs.

DESIGN, SETTING, AND PARTICIPANTS

These 2 separate retrospective cohort studies (The Health Improvement Network [THIN] and Optum's Clinformatics Data Mart [Optum]) compared adults receiving statins with those not receiving statins at the time of intra-abdominal surgery. Individuals undergoing intra-abdominal surgery from January 1, 1996, to December 31, 2013, in the United Kingdom and from January 1, 2000, to December 31, 2016, in the US were included in the study. Those with obstructive events before surgery or a history of inflammatory bowel disease were excluded. Data analysis was performed from September 1, 2012, to November 24, 2020.

EXPOSURE

The primary exposure was statin use at the time of surgery.

MAIN OUTCOMES AND MEASURES

The primary outcome was ARCs, defined as small-bowel obstruction or need for adhesiolysis, occurring after surgery. Sensitivity analyses included statin use preceding but not concurrent with surgery, fibrate use, and angiotensin-converting enzyme inhibitor use. All analyses were adjusted for age, sex, and conditions associated with microvascular disease, such as hypertension, hyperlipidemia, obesity, and tobacco use; surgical approach and site; and diagnosis of a malignant tumor.

RESULTS

A total of 148 601 individuals met the inclusion criteria for THIN (mean [SD] age, 49.6 [17.7] years; 70.1% female) and 1 188 217 for Optum (mean [SD] age, 48.2 [16.4] years; 72.6% female). A total of 2060 participants (1.4%) experienced an ARC in THIN and 54 136 (4.6%) in Optum. Statin use at the time of surgery was associated with decreased risk of ARCs (THIN: adjusted hazard ratio [HR], 0.81; 95% CI, 0.71-0.92; Optum: adjusted HR, 0.92; 95% CI, 0.90-0.95). Similar associations were appreciated between statins and small-bowel obstruction (THIN: adjusted HR, 0.80; 95% CI, 0.70-0.92; Optum: adjusted HR, 0.88; 95% CI, 0.85-0.91).

CONCLUSIONS AND RELEVANCE

This study's findings suggest that, among individuals in 2 separate cohorts undergoing intra-abdominal surgery, statin use may be associated with a reduced risk of postoperative ARCs. Statins may represent an inexpensive, well-tolerated pharmacologic option for preventing ARCs.

Effect of statins on experimental postoperative adhesion: a systematic review and meta-analysis

Adhesion is a significant concern after surgery. Many researchers studied the anti-adhesive effect of statin, of which results were inconsistent. Thus, we purposed to perform a systematic review and meta-analysis to evaluate the effect of statins on postoperative adhesion in an experimental study. A comprehensive search was conducted using MEDLINE, EMBASE, and Google Scholar to identify animal studies that investigated the postoperative anti-adhesive effect of statins applied at the surgical area. Primary outcome measure was gross adhesion score. Secondary outcomes included microscopic adhesion score and tissue plasminogen activator (t-PA) activity. Totally, 298 rats from 9 animal studies (172 rats received statin therapy and 126 rats received placebo or no treatment) were included in the final analysis. The combined results showed that gross and microscopic adhesion scores were significantly lower in the statin group in comparison to the control group (standardized mean difference [SMD] = 1.65, 95% confidence interval [CI]: 1.02 to 2.28, P_chi² < 0.001, I² = 77.9%; SMD = 1.90, 95% CI: 1.10 to 2.79, P_chi² < 0.001, I² = 84.5%, respectively). However, there was no evidence of a difference in t-PA activity (SMD = -3.43, 95% CI: -7.95 to 1.09, P_chi² < 0.001, I² = 95.5%). In conclusion, statins were effective in preventing postoperative adhesion, as assessed based on gross and microscopic adhesion scores in rats.

A systemic review of randomized controlled studies about prevention with pharmacologic agents of adhesion formation in the rat uterine horn model

INTRODUCTION

Evaluation of treatment attempts in postoperative adhesion formation is pivotal for the prevention of several morbidities including infertility, pelvic pain, bowel obstruction, and subsequent intraoperative complications. The purpose of this systemic review was to assess the literature on the rat uterine horn model for adhesion formation and treatment modalities to prevent adhesion in the most frequently used experimental animal model.

MATERIAL AND METHODS

We performed a systemic review of publications from January 1(st) 2000 to December 31(st) 2013 via a PubMed search. A high number of agents were evaluated for the prevention of postoperative adhesion formation in the rat uterine horn model.

RESULTS

According to most of the studies, adjuvants such as antiinflamatuars, antiestrogens, antioxidants were effective to prevent adhesion formation.

CONCLUSIONS

Prevention of adhesion formation is pivotal and numerous types of agents were described in the literature were summarized in this review.

Evaluation of the effects of fulvestrant and micronized progesterone on the post-operative adhesion formation and ovarian reserve in rat model with immunohistochemical and biochemical analysis

OBJECTIVE

To evaluate the effects of fulvestrant and micronized progesterone on post-operative adhesion formation and ovarian reserve in a rat uterine horn adhesion.

METHODS

In this prospective randomized controlled trial, 32 female Wistar albino rats were randomly divided into four groups including control group (Group 1), the control adhesion group (Group 2), 1 mg/kg daily intramuscular fulvestrant received group (Group 3) and 1 mg/kg daily oral micronized progesterone received group (Group 4). The extent and severity of adhesions were scored and samples were taken from adhesion areas to investigate the grades of adhesions according to the immunohistochemical scoring system. Ovarian reserves were measured with anti-Müllerian hormone (AMH) and histological ovarian follicles count.

RESULTS

The extent, severity and total adhesion scores were reduced in all treatment groups compared to control adhesion group (Group 2). Similarly, immunohistochemical adhesion scores were lower in the treatment groups. AMH and follicle count were significantly found lower in adhesion groups compared with control group. However, treatment groups were found to have higher ovarian reserve compared to control adhesion group (Group 2).

CONCLUSIONS

Fulvestrant and micronized progesterone were found to reduce post-operative adhesion formations and have decreased detrimental effects of adhesion formation on ovarian reserve.

Dietary fish oil supplementation inhibits formation of endometriosis-associated adhesions in a chimeric mouse model

OBJECTIVE

To examine whether dietary fish oil supplementation reduces development of spontaneous endometriosis-associated adhesions using an established model.

DESIGN

Laboratory-based study.

SETTING

Medical center research laboratory. PATIENT(S)/ANIMAL(S): Disease-free women of reproductive age and nude mice.

INTERVENTION(S)

Women were not provided any intervention. Mice were randomized to receive fish oil supplementation or control diet.

MAIN OUTCOME MEASURE(S)

Experimental endometriosis was established in mice via injection of human endometrial tissue within 16 hours of ovariectomy. Mice were provided standard or menhaden fish oil-supplemented diets for ≥ 2 weeks before initiation of experimental endometriosis and until killing them 1 week later. At necropsy, mice were examined for the presence and extent of adhesions and endometriotic-like lesions. Tissues were excised and morphologically characterized.

RESULT(S)

Adhesions/lesions were reduced in mice provided with dietary fish oil compared with control animals. Leukocytes were more numerous within the adhesions/lesions of the mice maintained on the standard diet compared with animals provided with fish oil. As indicated by staining intensity, collagen deposition was greater at adhesion sites within control mice compared with fish oil-supplemented animals.

CONCLUSION(S)

Wound-healing associated with surgery created an inflammatory peritoneal microenvironment that promoted the development of both experimental endometriosis and adhesions in a murine model. Targeting excessive inflammation with fish oil may be an effective adjuvant therapy to reduce the development of postsurgical adhesions related to endometriosis.

Pathogenesis of postoperative adhesion formation

Background

Current views on the pathogenesis of adhesion formation are based on the ‘classical concept of adhesion formation’, namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development.

Methods

A non-systematic literature search (1960–2010) was performed in PubMed to identify all original articles on the pathogenesis of adhesion formation. Information was sought on the role of the fibrinolytic, coagulatory and inflammatory systems in the disease process.

Results

One unifying concept emerged when assessing 50 years of studies in animals and humans on the pathogenesis of adhesion formation. Peritoneal damage inflicted by surgical trauma or other insults evokes an inflammatory response, thereby promoting procoagulatory and antifibrinolytic reactions, and a subsequent significant increase in fibrin formation. Importantly, peritoneal inflammatory status seems a crucial factor in determining the duration and extent of the imbalance between fibrin formation and fibrin dissolution, and therefore in the persistence of fibrin deposits, determining whether or not adhesions develop.

Conclusion

Suppression of inflammation, manipulation of coagulation as well as direct augmentation of fibrinolytic activity may be promising antiadhesion treatment strategies.

Metformin regresses endometriotic implants in rats by improving implant levels of superoxide dismutase, vascular endothelial growth factor, tissue inhibitor of metalloproteinase-2, and matrix metalloproteinase-9

OBJECTIVE

We sought to test if metformin could regress endometriotic explants in rats.

STUDY DESIGN

After inducing endometriotic implants and randomization of female Wistar albino rats, they were given 25 and 50 mg/kg/day of oral metformin in group A (n = 9) and B (n = 8), respectively, for 28 days. Group C (n = 9) was given saline as placebo.

RESULTS

Mean volume, weight, and histologic score of implants in groups A (P < .01, P < .05, and P < .05, respectively) and B (P < .01, P < .05, and P < .05, respectively) were significantly lower than in group C. The activity of superoxide dismutase and tissue inhibitor of metalloproteinase-2 staining in groups A (P < .05 and P < .01, respectively) and B (P < .01 and P < .01, respectively) was significantly higher than in the control group. Moreover, there were more significant reductions in implant levels of vascular endothelial growth factor and matrix metalloproteinase-9 in groups A (both P < .001) and B (both P < .001) than in group C.

CONCLUSION

Metformin causes regression of endometriotic implants in rats.

A randomised controlled trial on melatonin and rosiglitazone for prevention of adhesion formation in a rat uterine horn model

PURPOSE

To investigate the effectiveness of melatonin and rosiglitazone in reducing postoperative adhesion formation in a rat uterine horn model.

METHODS

Thirty non-pregnant female Wistar albino rats, weighing 180-220 g, were used as a model for postoperative adhesion formation. The rats were randomised into three groups after seven standard lesions were inflicted in a 2-cm segment of each uterine horn and lower abdominal sidewall using bipolar cauterisation. The rats were treated with 10 mg/kg, intraperitoneal melatonin, and 1 mg/kg per day peroral rosiglitazone. No medication was given to the control group. As much as 20 uterine horns of 10 rats were evaluated in each group. Extent, severity, and degree of the adhesions to the uterine horns and, inflammation and fibrosis scores (histopathologically) were evaluated after 2 weeks of the treatment.

RESULTS

There was no mortality in the groups and all of the rats recovered without incident after operation. Rosiglitazone group had lower adhesion scores [median (min-max ranges)] regarding extent, severity, and degree of the adhesions [0 (0-3), 0 (0-3) and 0 (0-3), respectively], which were significantly different (P < 0.001, P < 0.05 and P < 0.01, respectively) from those of the controls [1 (0-3), 2 (0-2) and 2 (0-3), respectively]; however, there were no statistically significant differences between rosiglitazone versus melatonin groups [1 (0-4), 2 (0-3) and 1 (0-3), respectively] and melatonin versus control groups. Moreover, no significant differences were determined between groups regarding histopathologic findings.

CONCLUSION

Rosiglitazone, but not melatonin, is effective in prevention of adhesion formation in a rat uterine horn model.